Pathologic nodal staging score for bladder cancer: a decision tool for adjuvant therapy after radical cystectomy.

BACKGROUND: Radical cystectomy (RC) with pelvic lymph node dissection (PLND) is the standard of care for high-risk non-muscle-invasive and muscle-invasive bladder cancer (BCa).
OBJECTIVE: To develop a model that allows quantification of the likelihood that a pathologically node-negative patient has, indeed, no positive nodes. DESIGN, SETTING, AND PARTICIPANTS: We analyzed data from 4335 patients treated with RC and PLND without neoadjuvant chemotherapy at 12 international academic centers.
INTERVENTIONS: Patients underwent RC and PLND. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We estimated the sensitivity of pathologic nodal staging using a beta-binomial model and developed a pathologic (postoperative) nodal staging score (pNSS) that represents the probability that a patient is correctly staged as node negative as a function of the number of examined nodes. RESULTS AND LIMITATIONS: Overall, the probability of missing a positive node decreases with the increasing number of nodes examined (52% if 3 nodes are examined, 40% if 5 are examined, and 26% if 10 are examined). The proportion of having a positive node increased proportionally with advancing pathologic T stage and lymphovascular invasion (LVI). Patients with LVI who had 25 examined nodes would have a pNSS of 80% (pT1), 88% (pT2), and 66% (pT3-T4), whereas 10 examined nodes were sufficient for pNSS exceeding 90% in patients without LVI and pT0-T2 tumors. This study is limited because of its retrospective design and multicenter nature.
CONCLUSIONS: We developed a tool that estimates the likelihood of lymph node (LN) metastasis in BCa patients treated with RC by evaluating the number of examined nodes, the pathologic T stage, and LVI. The pNSS indicates the adequacy of nodal staging in LN-negative patients. This tool could help to refine clinical decision making regarding adjuvant chemotherapy, follow-up scheduling, and inclusion in clinical trials.